1. Field of the Invention
The present invention relates to power line communications, more particularly to DC (direct current) powerline communication (PLC) networks, and AC (alternating current) to DC (direct current) powerline communication (PLC) interfaces.
2. Description of the Related Art
Powerline communication (PLC) network technology allows the transfer of computer data signals over power lines, such as alternating current (AC) powerlines commonly found in residential and office buildings. Powerline communication network technology facilitates the networking of (i.e. providing of data interconnectivity within) homes and offices without the additional installation of dedicated Ethernet cables or the reduced reliability and security concerns that come with wireless networks.
For an overview of powerline communication network technology see Powerline Communications by Klaus Dostert (Prentice Hall, ISBN 0-13-029342-3).
An example of a powerline communication network technology uses the X10 protocol to transfer data over AC power lines. The X10 protocol is commonly used for home operated devices, such as lights and switches. In the X.10 standard, the transmission of data is synchronized to the zero crossing of the AC signal using a 120 kHz tone burst superimposed on the AC signal. The home operated devices filter and decode these tone bursts to initiate commands that control the properties of these devices.
Another example of a powerline network technology uses the HOMEPLUG™ (Homeplug Alliance) protocol (see www.homeplug.org). The Homeplug protocol is designed to transfer information for devices that use such standards as HDTV, SDTV, and audiophile quality stereo in the house. The simplicity of installing consumer products, simply by plugging in a device, is important feature of the standard.
The Homeplug standard data is synchronized on the zero crossing of the AC signal. As the voltage on the line rises, Data is transferred with a superimposed AC signal ranges from 1-30 MHz. The frequency of this superimposed signal allows an effective payload transfer transfer rate of about 50-60 Mbs.
Heretofore, powerline communications are designed to operate on AC power supply lines. In the United States this is typically 120 Volts AC operating at 60 Hz. In most European countries the voltage is 220-240 Volts AC operating at 50 Hz. In Japan the voltage is 100 Volts AC operating at both 50 Hz and 60 Hz.
In accordance with heretofore known power communications networks, network communication signals are introduced into the 100-240 Volts AC power supply lines via a powerline communications transceiver. These network communication signals may originate either with the power utility provider (external to the structure) or by a device that is internal to the residential, office building, or campus of buildings. These data signals are then received and processed by a powerline communications transceiver. The powerline communications transceiver is connected to the powerline communications network through a plug that is inserted into an AC outlet in a conventional manner.